deepflame Hmm, are you sure these are fluorescent lamps? I have seen mostly LED tubes recently here in Germany. Not sure if they sell normal fluorescent tubes anymore.
Hey, I thought of sharing additional details I got, in case you and/or someone else is interested.
All the lamps I tested, "good" and "bad", are of exactly the same type (Panasonic FHF32EXLH), which explains why with the spectrometer I did not detect spectral differences.
The light color is called "electric bulb" (there are eventually other variants with different colors, e.g., natural, white, etc. etc., which are not installed anywhere at work, as far as I know).
From another document - which is only in Japanese - I see (ehm, I guess) that the color temperature is 3000K.
Looking more deeply at the specs I infer that there are either two subtypes of FHF32EXLH lamps or the same tube can be run two ways, low and high power, namely, 32W / 0.255 A / 3520 lm / 3000 K and 45W / 0.425 A / 4950 lm / 3000 K, respectively. Note that the color temperature is the same.
The facility people who take care of the lighting confirmed the lamps in the office ("bad') are dimmer than the ones in the labs ("good"). Hence I conclude that the "good" lamps are the high power ones, and the "bad" lamps the low power ones. Color temperature is the same (--> same wavelengths in my spectra), and is very low so there should not be much blue light. Then what can the trigger of my eyelid twitching and eyestrain and migraines be? I do not see any plausible reason why a small luminous flux triggers symptoms and a larger flux of the same spectrum does not. I can only think that running the tube low power causes more (imperceptible to most) flickering.
Any thought is greatly appreciated!